<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
  <title>bootstrap4</title>
  <link type="text/css" rel="stylesheet" href="css/base.css">
  <link type="text/css" rel="stylesheet" href="https://cdn.staticfile.org/bootstrap/4.6.0/css/bootstrap.min.css">
  <style>
    .item{
        border-radius: 5px;
        background-color: #b3dfea;
        margin-top: 5px;
    }
    .tran{
        border: #111111 solid 50px;
        height: 0;
        width: 0;
        border-bottom-;
    }
  </style>
</head>
<body>
  <div class="container">
    <div class="row">
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">1</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">2</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">3</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">4</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">5</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">6</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">7</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">8</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">9</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">10</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">11</div>
      <div class="item col-xl-1 col-lg-2 col-md-3 col-sm-4 col-12">12</div>
    </div>
    <div class="row">
      <div class="item col-4 ">1</div>
      <div class="item col-4 offset-md-4">1</div>
      <div class="item col-6">1</div>
      <div class="item col-4">1</div>
    </div>
    <div id="progress" class="progress">
      <div class="progress-bar progress-bar-striped progress-bar-animated" style="width:45%"></div>
    </div>

  </div>
  <div class="tran"></div>
</body>
<script src="https://cdn.staticfile.org/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdn.staticfile.org/popper.js/1.15.0/umd/popper.min.js"></script>
<script src="https://cdn.staticfile.org/bootstrap/4.6.0/js/bootstrap.js"></script>
<script>
  var progress = $("#progress > .progress-bar");
  console.log(progress);
  let bar = 0;
  let interval;
  interval = setInterval(function(){
    if(bar < 100){
      bar = bar + 1;
    }else{
      interval.clear();
    }
    progress[0].style = "width:"+bar+"%";
  },1000)
</script>
</html>